Scientists theorize that australia was once part of a larger mainland area but due to plate tectonics, broke away. according to island theory, scientists can explain all but one of these occurrences as a result of australia becoming and staying an island for a very long time. that is
a) extremes in size, large or small.
b) the evolution of flightless birds.
c) the presence of relics, like the marsupials.
d) a large assortment of plant dispersal mechanisms.

How are mutations continually being generated in a population (what are some of the causes of mutatuions? ) explain

Astudy by solloch and et. al., in 2017, gives the map above which shows the frequency of alleles with a ccr5-delta32 mutations over 87 different countries. this mutation deletes the presence of a co-receptor (ccr5) on the outside of human t-cells (lymphocytes). some viruses, such as the one responsible for the black death and human immunodeficiency virus (hiv), require this receptor for attachment to host cells during the infection process. the black death was an epidemic that passed over northern europe during the 14th century killing nearly 60% of europeans. according to this information, which explanation best explains why northern europeans show a greater immunity for hiv than some other parts of the world?

Which level of taxonomy has the fewest organisms?